1. Industrial Field of the Invention
The present invention relates to a canister for adsorption of evaporated fuel in an automobile.
2. Description of the Related Art
Conventionally, a canister serves to adsorb fuel vapor which is evaporated in a fuel tank when an engine of an automobile is stopped or when a vehicle is running, by activated carbon contained in the canister so as to supply the adsorbed evaporated fuel to the engine during operation of the engine. The canister includes an adsorption port communicating with a fuel tank, which adsorption port is provided on the upper or lower side of the canister main body containing the activated carbon therein. The canister also includes a purge port communicating with an intake manifold and an atmosphere port in communication with an atmosphere on the lower or upper side of the canister.
In the above-described prior art, high boiling components in the evaporated fuel are adsorbed by the activated carbon and accumulated in the canister, so that deterioration of the activated carbon is accelerated. Thus, the conventional canister has such a disadvantage that the adsorbing capability of the canister is lowered when it is used for a long time.
The fuel vapor is diffused in the container of the canister when the canister is left as it is for a long time. The diffused fuel vapor is forcibly discharged by the fuel vapor which has newly come into the canister. Also, when the temperature of the atmosphere surrounding the canister rises, the evaporated fuel vapor expands. Accordingly, even if the canister has adsorbed only a small amount of the evaporated fuel, the evaporated fuel unfavorably leaks through the atmosphere port of the canister into the atmosphere when the temperature of the atmosphere rises or when a small amount of the evaporated fuel enters the canister after the canister is left as it is for a long time.